Substantial bodies of water such as swimming pools, spas, and cooling towers require constant attention to the elimination of undesirable organic material such as waste material, organic compounds, algae and bacteria. The infusion of gaseous chlorine or of hypochlorite ion is a conventional way to provide an oxidizing agent for this purpose.
There are two levels of attack. One is for the long term maintenance of an existing agreeable condition, in which the level of the oxidizing agent is kept low, and the substance is supplied at a slow steady rate. Examples are the use of slowly dissolving tablets of the oxidizing agent placed in the body of water or in a recirculating system supplying it, or in a slow but steady stream of an oxidizing substance, such as gaseous chlorine, hypochlorite solution, oxygen, peroxides and ozone.
The other level of attack is when the conditions in the body of water have deteriorated to the point where a slow supply is insufficient to eliminate the problem, and in which a vigorous attack must be made. In such event, a large amount of oxidizing agent is added to the body very quickly, so that the chlorine concentration rises well above that which would be maintained during routine operations. Such a treatment is called a "shock" treatment by persons familiar with this art.
Especially for domestic bodies of water, but also for many other substantial-sized bodies of water such as cooling towers, the amount of chemicals needed for a shock treatment is relatively small in weight and bulk, and would most conveniently be provided in small containers or pouches. These must be packaged to have a reasonable shelf life, and be agreeable when the package is opened. The best situation would be if the product were safe to store and handle as well as easy to use.
There are many products which from a chemistry standpoint can be used for shock treatment. Aqueous hypochlorite solutions are a familiar example. A pervasive problem is the bulk which must be handled, and the rapid loss of chlorine. Sources of treatment gas such as chlorine and ozone require capital installations and handling of hazardous materials.
In contrast, trichloro compounds would be preferable because of their substantial chlorine content, safety in handling and convenience. Still they are slow to dissolve.
This property of slow dissolving is ideal for long-term maintenance, and is the principal reason why trichloroisocyanuric acid (hereinafter called "trichloro") is so frequently used in compressed tablets kept submerged in a swimming pool or in a feeder. The trichloro in a tablet form will dissolve very slowly, and will maintain a steady, slow chlorine release for a long period of time when that characteristic is desirable. However, its slow dissolving rate, even in finely divided form, is a contraindication against its use for shock treatment because immediate chlorine release is the objective. An additional complication occurs because trichloro when finely grained simply floats and coagulates on the surface of the water for a long period of time, and when finally wetted, the clusters sink to the bottom where they dissolves slowly.
Trichloro has a substantial advantage in its stability while dry, and in its low flammability. Except for the fact that unassisted it is useless for a shock compound, it would be an ideal domestic source of chlorine for this application.
In contrast, dichloroisocyanurate (hereinafter called "dichloro") is readily soluble, and is used for shock treatments. Its disadvantages compared to other chlorine compounds include, but are not limited to a higher price, lower relative available chlorine and the potential fire hazard of the anhydrous form. Its only comparative advantage is its speed of solution into water, which is rapid. For this reason it is used for shock treatments despite its disadvantages.
This situation has not gone unnoticed, and efforts have been made to provide mixtures of trichloro and other chemicals, which provide pathways by which the chlorine in trichloro can quickly be released. These arrangements have brought with them a number of problems, because characteristically they include substances which will react with trichloro to reduce it to the more soluble dichloro when in the water, or which provide other reaction paths involving reactants that must be stored together with the trichloro so as to be available for the intended reaction. Accordingly, when used, trichloro has generally been accompanied by substances which bring their own expense and problems. The result of all of this is that trichloro has generally been disfavored for use in shock treatment of large bodies of water.
It is an object of this invention to provide a mixture of trichloro and a small amount of another substance to be described which mixture is stable, safe to handle, does not constitute a flammability risk, has a relatively lower toxic risk and which dissolves very quickly.
This composition is intended for use in substantial volumes of water in which the composition will be dissolved in an unbounded but very local region, from which it disperses into the larger volume. It is not intended as a local oxidizer or cleanser for surfaces, or as a solution for direct use on anything, but instead is intended for infusion into the substantial volume very quickly after the trichloro is dissolved, thereby to provide a quick increase in chlorine in the substantial body of water.
There is yet another problem inherent in the use of trichloro. It has so much chlorine content per unit of weight or volume that a small amount of it suffices for a very large body of water. For example, 6 ounces of trichloro will suffice to shock treat a swimming pool containing 12,000 gallons of water, raising its chlorine concentration by about 3 ppm.
The small size of this portion presents the problem of providing to the consumer an amount of the product which can be used at one (1) pound per 12,000 gallons of water (a traditional premium consumer product dosage rate) for shock treatment. Accordingly, a bulking agent may be provided as an inert diluent so a dose can be presented to the consumer in a single package and in a condition such that he can readily transfer it from the package, such as a plastic pouch, to the body of water. In addition the dose delivered is accurate, much more accurate than if a small amount of the trichloro were measured out of a larger container.
The bulking agent is inert relative to the dissolving of the trichloro into the water, and to its release of oxidizing agent. Its purpose is not to assist these functions, but to dilute the trichloro by weight for both dose control and affixing an acceptable price per pound. However if this inert diluent can also provide other advantages such as reduction (or practical elimination) of flammability or to stabilize the active ingredients, or clarify the water (or condition the water) so much the better.
It is an object of this invention to accompany trichloro with a substance which will accelerate its solution without taking part in the chlorine release, and if desired, to provide additives as bulking agents, and other additives which provide other water treatment properties in addition to those provided by the released chlorine, but which take no part in the release of the chlorine or dissolving of the trichloro.